A rewinder of this type is described, for example, in U.S. Pat. No. 4,487,377.
These rewinders are used for producing smaller diameter logs or rolls of web material from large diameter parent rolls. Typically, these machines are used in the paper converting industry to produce rolls of toilet paper, kitchen towels, all-purpose wipers and the like. The formed logs may be as long as 350 cm and only 10-15 cm in outer diameter, and are subsequently cut transversely to their axis to obtain small rolls which may be only 10-30 cm long.
In the production of such logs, it is important to use reliable machines able to run at high production speeds (in the range of 600-1000 m/minute) which provide a consistently high-quality product, with uniform windings, especially of the first loops. The length of the material on each log must be presettable and maintained, from log-to-log, with great accuracy.
One way to obtain high production rates and a high quality of the manufactured product is shown in U.S. Pat. No. 4,487,377, which provides for a web-cutting member which cooperates with the first winder roller of the rewinder. The web material is cut upstream of the point where the core is introduced. After cutting, the leading edge of the web material adheres to the surface of the winder roller and is transferred (by the rotation of the latter) towards the winding region where the leading edge is made to adhere to a new core suitably introduced by an insertion means.
This machine requires means (for holding the leading edge of the web material onto the winder roller) which are housed inside the winder roller and which must be timely activated and deactivated to hold and release the edge at preset moments, thereby allowing the starting of the winding on a new core.
In U.S. Pat. No. 4,327,877 a machine is described, wherein the web is torn between the core and the second winding roller once the core has been introduced into the nip. Tearing is obtained by a suction means inside the second winding roller. The suction means forms a loop of web material which is pinced between the new core and the second roller.